棉花三元杂种的细胞遗传学研究

棉属有丰富的种质资源,在野生棉种中有许多优异的农艺性状和丰富的基因资源,将野生澳洲棉和黄褐棉的优良性状导入陆地棉,以期改良栽培种陆地棉。采用栽培种陆地棉和野生澳洲棉杂交获得杂种F1,然后对其进行染色体加倍,加倍后的异源六倍体再与野生黄褐棉杂交,产生陆地棉、澳洲棉和黄褐棉的三元杂种,并对三元杂种F1花粉母细胞减数分裂行为进行观察。结果表明:三元杂种F1的减数分裂异常,主要表现在减数分裂后期染色体不能均等分离,在四分体形成时期,常出现一些多分体和微核。统计结果表明,末期Ⅱ形成的异常型孢子占绝大多数,而其正常的四分孢子数仅占8.4%,导致最后不能形成正常的花粉粒,这是三元杂种不育的主要原因。研究结果为三元杂种不育提供了细胞遗传学证据,也为棉花新种质的创制提供了中间材料。

Cytogenetic Study on Trispecific Hybrid in Gossypium

There are rich germplasm resources in Gossypium.Wild cotton species have many valuable agronomic traits which present excellent genes perform.In order to introgress the useful traits from wild species G.australe and G.mustelinum into cultivated species,tetraploid G.hirsutum was crossed directly with G.australe,resulting in a triploid hybrid.The chromosomes of （G.hirsutum × G.australe） F1 were doubled and then crossed with AD-genome wild species G.mustelinum,synthetizing trispecific hybrid （G.hirsutum,G.australe,G.mustelinum）.Meiosis behavior of this trispecific hybrid was observed from its pollen mother cells （PMC）.Results showed that chromosomes separa ted unevenly in anaphase of abnormal meiosis.Some multispores and micronucleus often appeared during the formation of tetrad in PMC.Abnormal spores formed in telophase Ⅱ accounted for the majority while normal tetraspores just for 8.4％,resulting in the formation of abnormal pollen grains.This study provided the main cytogenetic evidence for the sterility of trispecific hybrid,and supplied the intermediate material for new breeding program.